It's hard to say but if the air entering, or exhausing or gathering at or around the vent, is warm/hot, AND if there's moisture in that air, then it's possible that this is the cause of the mold.
Mold/mildew needs warm, moist air to grow. It doesn't have to be occurring constantly. It could come and go. In fact, I get mildew on the backside of my home every year. It doesn't occur in Winter but it does occur in Summer. Point is - Find the source of the warm, moist air, and you'll find the cause. As to what you should do about it, yes, perhaps a low-powered gable fan is OK. You only need enough draw to pull the air out. DON'T suck air into the attic! This would most likely add to your problem.
Do you have a bathroom vent that's exhausting into the attic space? If so, this is bad. Is there an air 'leak' from the living space into the attic space? If so, close it off.
My best to ya and hope this helps.
Jay J -Moderator
PS: God Bless America!
I have noticed mold or mildew (and what is the difference between the two) in our laundry room air conditioning vent and on the ceiling around it; on the master bathroom air conditioning vent; and on the master bedroom air conditioning vent. Can you tell me how to correct this on our own or even where to start?
Also, mold does not require warmth to grow. Warmer air can be humid where as colder air contains less moisture.
To a mycologist the definition of mildew is for a growth produced by mold.
I'm trying to put this in simple terms, however a true definition is not a simple.
I do not think most home owners are qualified to properly address mold in their homes. Improper actions taken by an uneducated DIY'er can make the matter worse and spread the mold to other areas of the home.
Mold can be dangerous, do not risk your health when it comes to mold, seek out a true professional.
I do not consider most ServPro employees mold experts, nor are most carpet cleaning agents that do mold work on the side.
There are home testing kits we've seen at Home Depot and Lowe's. I'm not sure those are even worth it, though, considering what we see with our own eyes.
I've now noticed that whatever the "spots" are, they started in the laundry room (where it's not in a couple of spots right on the edge of the vent cover on the ceiling), but it has spread to the vent covers in the closest rooms/spaces to the laundry room.
What type of service professional do we call to at least have this checked out? I do not know where to even start.
A current client just called me after buying and using a mold test kit from Home Depot. I have the results on my desk right now. The method used in these kits consist of trapping spores that fall from the air. This method is not considered to be viable and often will not give you any conclusive information.
Since mold spores can be found in every room of a house, it is haphazard as to which spores will be found in the trap and may not be indicative of what type of mold you have in the problem area. Every time you open a door or window there is a possibility of letting outdoor spores in the house, the sampling method is just too random.
Also, what do you do with the information once you know you have mold?
Any remediation company worth their salt would not use your sample/test results as a way of correcting your mold problem.
I like to perform atleast 3 tests in a home. Below is a minimum.
1. Air Sample - Outside to determine a baseline of what types of mold are naturally in your surroundings.
2. Air Sample - Inside the house in the area of visible mold to compare against the baseline sample.
3. Swab Sample - Tactile sample of the actual visible mold.
In some cases these three samples will allow us to accurately assess the house and determine if there are any health risks. This will also allow us to develope a plan of action for remediation.
Most likely if the mold has spread like you stated, it is caused by mold spores migrating onto surfaces that contain organic matter (dusty). The humidity levels in the room must be high enough to allow the mold to flourish.
I am in the Boston area and alway run up against "mold experts" that have very little knowledge of mold and use less than appropriate methods of remediation. Most of these contractors will not warranty their work if mold comes back, so make sure you do not sign a contract that is full of loop holes.
I have a microbiologist on staff, so you should look for a contractor with the same.
I do have a dehumidyfier in this basement. There are not open drains in this basement.
I was just talking with a client about something like this. One of his tenants pulled a picture out of the trash then hung it on the wall. After a while the picture was removed and there was mold on the wall in the exact shape of the picture. This is what we call cross contamination. I have seen entire houses infectred because the owner brought mold contaminated cardboard boxes out of the basement and placed them in closets around the house.
There are so many factors that unless I inspect the area, it is all a guess.